The present invention relates generally to a back-up pad for supporting an abrasive article and to methods of making such a back-up pad. The present invention relates more particularly to a back-up pad having a dust collection groove, in which the engagement component for securing the abrasive article is attached to the dust collection groove surface.
Abrasive articles have long been used in industry for abrading, grinding, and polishing applications. They can be obtained in a variety of converted forms, such as belts, discs, sheets, and the like, in many different sizes.
Generally, when using abrasives articles in the form of xe2x80x9csheet goodsxe2x80x9d, i.e. discs and sheets, a back-up pad is used to mount or attach the abrasive article to the abrading tool. Back-up pads are well known in the abrasive art and are described, for example, in U.S. Pat. No. 5,692,949 (Sheffield et al.) and PCT publication WO 97/20662 (Keipert), published on Jun. 12, 1997. Known back-up pads usually have one side on which an abrasive article, such as a disc, is attached. The other side of the back-up pad generally has a screw or other fastener extending therefrom to attach the back-up pad to a power tool.
Two common methods of attaching abrasive discs and sheets to back-up pads include pressure sensitive adhesives and hook and loop fasteners. When the attachment means is a hook and loop system, the abrasive article will have either loop or the hook component on the backing surface opposite the abrasive coating, and the back-up pad will have the complementary mating component, i.e., the hook or loop. An example of abrasives with a hook and loop fastener is available from Minnesota Mining and Manufacturing of St. Paul, Minn. under the trade designation xe2x80x9cHookitxe2x80x9d or xe2x80x9cHookit II.xe2x80x9d When the attachment means is a pressure sensitive adhesive, the abrasive article will generally have the adhesive thereon and the back-up pad will typically have a smooth surface such as vinyl or rubber. An example of abrasives with a pressure sensitive adhesive attachment means is available under the trade designation xe2x80x9cStikitxe2x80x9d from Minnesota Mining and Manufacturing of St. Paul, Minn.
Back-up pads having dust collection grooves and dust collection holes are well known in the abrasive art and are described, for example, in U.S. Pat. Nos. 4,184,291, 4,779,385, and 4,759,155. Known back-up pads usually have dust collection grooves in the support surface of the back-up pad and include dust collection holes through the support surface which are in fluid communication with the dust collection grooves. The dust collection holes are typically connected to a vacuum source. The dust collection grooves and holes provide a passageway for removing dust, debris, or abrading fluid, such as water or oil, from the abrading surface.
Profile back-up pads are well known in the abrasive art. Known profile pads have contoured shaped support surfaces adapted to conform to the irregular surface of a work piece, such as wood trim or molding. However, such profile pads do not include dust holes or dust collection grooves for removing any dust, debris, or abrading fluid, such as water or oil, from the abrading surface.
In conventional back-up pads having dust grooves in their support surfaces, the engagement component attached to the support surface is two separate pieces. The first piece of the engagement component covers the central portion of the back-up pad up to the dust collection groove. The second piece of the engagement component covers the outer portion of the back-up pad extending between the dust collection groove and the outer edge of the back-up pad. When abrasive sheets are repeatedly attached and detached from the engagement component, the first piece and second piece of the conventional engagement component experience a high unit tension along the peripheral edges of the first piece and the second piece. The high unit stress is due to the force of detaching the abrasive sheet from the small area along the peripheral edges of the conventional engagement component. The high unit stress along the peripheral edges has a tendency to cause the first piece and second piece of the engagement component to delaminate from the support surface. Additionally, the conventional back-up pad includes sharp edges between the dust groove and the support surface because the dust groove is usually cut into the engagement component and support surface of the back-up pad after the backup pad is formed. The sharp edges of the conventional engagement component also have a tendency to delaminate from the support surface of the back-up pad.
The present invention provides a method of making a back-up pad for supporting an abrasive article. The method includes the steps of: a) providing a support member including a first major surface, and a second major surface opposite the first major surface, where the first major surface includes a support surface and a dust collection groove, and where the dust collection groove includes a groove surface; and b) attaching an engagement component to the first major surface of the support member and to the groove surface. In one preferred embodiment of this method, the method further includes the step of c) forming a hole through the engagement component and the support member, where the hole is in fluid communication with the dust collection groove. In another preferred embodiment of this method step c) includes forming a first plurality of the holes through the engagement component and the support member, where the first plurality of the holes is in fluid communication with the dust collection groove.
In yet another preferred embodiment of the above method, the engagement component includes a plurality of loops adapted for releasable engagement with a plurality of hooks on an abrasive article. In another preferred embodiment of the above method, the engagement component includes a plurality of hooks adapted for releasable engagement with a plurality of loops on an abrasive article. In still another preferred embodiment of the above method, the engagement component includes a smooth surface adapted for releasable engagement with a layer of adhesive on an abrasive article. In another aspect of this embodiment, the smooth surface comprises vinyl. In another preferred embodiment of the above method, the engagement component includes a self-mating fastener adapted for releasable engagement with a like fastener on an abrasive article.
In yet another preferred embodiment, step a) comprises molding a moldable material to thereby provide the support member. In another aspect of this embodiment, step a) further comprises molding the dust collection groove in the first major surface of the support member. In another aspect of this embodiment, the steps a) and b) further comprise placing the engagement component in a mold and introducing the moldable material into the mold, whereupon solidification of the moldable material, the engagement component is thereby attached to the first major surface of the support member and to the groove surface. In another aspect of this embodiment, the mold includes an annular protrusion for forming the dust collection groove in the first major surface of the support member. In yet another aspect of this embodiment, the method further includes the step of imparting a groove in the engagement component prior to placing the engagement component in the mold, and where the groove in the engagement component corresponds to the dust collection groove in the first major surface of the support member.
In another preferred embodiment, the above method further includes the step of imparting the dust collection groove on the first major surface of the support member after molding a moldable material to provide the support member. In another preferred embodiment of the above method, a hole is at least partially molded through the support member. In yet another preferred embodiment, the moldable material comprises a resilient foam material. In another aspect of this embodiment, the resilient foam material comprises open cell polyurethane foam.
In another preferred embodiment, the above method further includes the step of placing a drive member in the mold prior to introducing the moldable material to thereby attach the drive member to the second major surface of the support surface. In another preferred embodiment, the above method further includes a step prior to step b) of: forming a groove in the engagement component corresponding to the dust collection groove in the first major surface of the support surface, where step b) further includes aligning the groove in the engagement component with the dust collection groove in the support surface.
In another preferred embodiment of the above method, the support member includes a drive member attached to the second major surface of the support member. In yet another preferred embodiment, the dust collection groove in the first major surface of the support member comprises an annulus. In another preferred embodiment of the above method, the first major surface of the support surface comprises a plurality of grooves. In still another embodiment of the above method, the groove in the engagement component is at least 0.15 cm in depth.
The present invention also provides a back-up pad for supporting an abrasive article. The back-up pad comprises: a) a support member including a first major surface, where the first major surface includes a support surface and a dust collection groove, and where the dust collection groove includes a groove surface; and b) an engagement component attached to the first major surface of the support member and to the groove surface.
In a preferred embodiment, the above back-up pad further includes a hole through the engagement component and the support member, where the hole is in fluid communication with the dust collection groove. In another preferred embodiment of the above back-up pad, the back-up pad is in combination with a motor drive source and a vacuum source, where the support surface includes a second major surface opposite the first major surface, where the back-up pad further includes a drive member attached to the second major surface of the support member, where the drive member on the second major surface of the support member is connected to the motor drive source, and where the hole is in fluid communication with the vacuum source.
In another preferred embodiment of the above back-up pad, the back-up pad further includes a plurality of the holes through the engagement component and the support member, where the plurality of the holes are in fluid communication with the dust collection groove.
In another preferred embodiment of the above back-up pad, the engagement component comprises a plurality of loops adapted for releasable engagement with a plurality of hooks on an abrasive article. In another preferred embodiment of the above back-up pad, the engagement component comprises a plurality of hooks adapted for releasable engagement with a plurality of loops on an abrasive article. In another preferred embodiment of the above back-up pad, the engagement component includes a self-mating fastener adapted for releasable engagement with a like fastener on an abrasive article. In another preferred embodiment of the above back-up pad, the first major surface of the engagement component comprises a smooth surface adapted for releasable engagement with a layer of adhesive on the abrasive article. In another aspect of this embodiment, the smooth surface comprises vinyl.
In another preferred embodiment of the above back-up pad, the support member comprises a moldable material. In another aspect of this embodiment, the moldable material comprises a resilient foam material. In another aspect of this embodiment, the resilient foam material comprises open cell polyurethane foam.
In another preferred embodiment of the above back-up pad, the support member further includes a second major surface opposite the first major surface, and where the back-up pad further includes a drive member attached to the second major surface of the support member. In yet another preferred embodiment of the above back-up pad, the dust collection groove in the support surface comprises an annulus. In another preferred embodiment of the above back-up pad, the support surface includes a plurality of the dust collection grooves each including a respective groove surface, and where the engagement component is attached to the plurality of groove surfaces. In still another preferred embodiment of the above back-up pad, the distance between the portion of the engagement component attached to the first major surface of the support member and the portion of the engagement component attached to the groove surface is at least 0.15 cm.